Toews studied at the University of Manitoba and the University of King's College in Halifax, and has also worked as a freelance newspaper and radio journalist. Her non-fiction book Swing Low: A Life was a memoir of her father, a victim of lifelong depression. Her 2004 novel A Complicated Kindness was her breakthrough work, spending over a year on the Canadian bestseller lists and winning the Governor General's Award for English Fiction. The novel, about a teenage girl who longs to escape her small Russian Mennonite town and hang out with Lou Reed in the slums of New York City, was also nominated for the Giller Prize and was the winning title in the 2006 edition of Canada Reads.

A series of letters she wrote in 2000 to the father of her son were published on the website www.openletters.net and were profiled on the radio show This American Life in an episode about missing parents.

In 2007 she made her screen debut in the Mexican film Luz silenciosa directed by Carlos Reygadas, which screened at the Cannes Film Festival. She was nominated for Best Actress at Mexico's Ariel Awards for her performance in the film.

In September 2008, Knopf Canada published her novel The Flying Troutmans, about a 28-year-old woman from Manitoba who takes her 15-year-old nephew and 11-year-old niece on a road trip to California after their mentally ill mother has been hospitalized. That novel won the 2008 Rogers Writers' Trust Fiction Prize.